Last week a buddy and I did a three-day, 30 mile, unsupported hike out in Big Bend backcountry. This involved carrying 6 liters of water (each, per day) to make the 6-7 hour hike from one spring to the next. The trail included multiple 1000-3000' inclines. It was brutal but beautiful country.

The original plan was to purify the spring water by boiling, but once we realized the amount of fuel and time required, that process became a no-go. We both carry Life Straws but they are a cumbersome way to drink while on the move. Another backpacker buddy suggested a Grayl GeoPress, which works kind of like a coffee French press, but with a super filter system. One fills the outer bottle with raw water, inserts the inner bottle with filter on the bottom, and slowly presses the inner bottle into the outer bottle. In about 30 seconds you have turned scum-covered water filled with bird poop into 750mL of clean, clear, tasty, cool water! It took us 20 minutes to fill twelve one-liter bottles, and that included drinking a lot of the water we were producing.

The Grayl was a gamechanger, especially when we reached the last spring and discovered it was dry. We had to hike to a band of cottonwoods (sign of water in the Southwestern deserts) and dig a hole under them to get water. By then we were partially dehydrated. Once the Grayl purified this water we could drink it without having to wait for it to cool down from boiling. Truly a lifesaver!

According to the Grayl specifications, the filter system removes bacteria, spores, viruses, pesticides, herbicides, heavy metals, and other common, North American contaminants from up to 250 gallons of raw water. It can NOT make brackish or salt water drinkable. Using a bandana to pre-filter sediment and debris from the water helps prolong the life of the filter. The inner bottle has a tight seal so you can carry it filled with the filtered water without worry of it leaking.

Amazon Affiliate* link to Grayl GeoPress: https://amzn.to/347HIrk
-Blast

I have so far only used my Geopress to make foultasting tapwater taste neutral in Tallinn. It is drinkable and won´t make you ill but the taste is not good.

Nice! I've read good things, might have to try one.

I'm starting to really like this guy's videos. Here he reviews the Grayl Geopress.

https://youtu.be/tpd0tHdZGCw

He makes a good point about mucky water plugging the Grayl's filter. Areas like that would demand pre-filtering or maybe even flocculation with some alum. Here's information on backpacking water treatment flocculation: https://backpackinglight.com/alum-water-clarification-backpacking/

-Blast

For my Geopress I have a Millbank bag to prefilter the water incase I need to filter mucky water.

I think it is conventional to use coffee filters for prefitering. That should get all but very quite fine particles out.

Looking at the Geopress, basic specs are: 24 oz built-in bottle, costs $100, weight 450g, filters 5L/minute. There is a smaller version with 16oz bottle weighing 354g that does 3L/minute, and a 2L/minute 309g model, both of which cost a little less. The manufacturer website is grayl.com.

I had not heard of this before and it seems nicer than the old Katadyn and MSR stuff that I've looked at. Thanks!

Having a Grayl myself, I would say no way you can filter 5 liter/minute. I´d say 2 liter at the most per minute.